The present invention addresses the packaging box industry and, in particular, relates to a machine for covering boxes with a pre-glued sheet.
In prior art, covering sheets are applied to formed boxes using machines known as “gluing machines”.
Examples of these machines form the subject matter of patents IT1224973 and IT1269105 to the Applicant.
These machines comprise a conveying system which transports the box to a covering unit which applies the glued sheet to the walls of the box in such a way as to completely cover the box.
At present, prior art covering machines rollers or brushes which move vertically relative to the outside walls of the box and which move the edges of the covering sheet into contact with the corresponding walls of the box.
To complete the box covering, there are also pressing means that move close to the outside surfaces of the box and horizontal blades that line up with the upper edges of the walls to be covered.
The blades can move relative to the pressing means and, once the pressing means have moved close to the box, they continue moving towards the box and push the edges of the covering sheet over the free upper edges of the box in such a way that the edges of the covering sheet protrude towards the inside of the box.
Next, the blades are moved away from the box again and a suitably shaped pad is inserted into the box in such a way as to press the edges of the covering sheet against the inside walls of the box.
Lastly, once the boxes have been covered completely, the boxes are fed out of the covering machine.
These prior art covering machines, however, are unsuitable for use on boxes with irregularly shaped sides, that is to say, when the wall to be covered is not perpendicular to the direction in which the pressing means and blades move towards the box or when the wall to be covered is at an angle to the horizontal, thus making it difficult to use horizontal folding blades.
Up to now, boxes of this kind were dealt with using manual expedients such as, for example, wedges or shims to adapt the position and angle of the pressing means and blades to the shape of the box.
Obviously, the need for manual operations involves higher costs and less precision and repeatability.